3.2.11 Noble metals

LeClaire, A. D.; Neumann, Gerhard

doi:10.1007/10390457_39

Cited by 3 publications

(2 citation statements)

References 52 publications

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“…Hence, diffusion of Ge (in a-Cu(Ge)) is most likely not a transformation-rate determining process. (c) If yet a diffusion-controlled growth mode is adopted in the fitting, the value obtained for the activation energy for diffusion of Ge in Cu (94.0 ± 5.5 kJ mol À1 ; see Table III), is distinctly lower than the literature value (185 kJ mol À1 for diffusion of Ge through pure Cu single crystals [34,35] ), which is compatible with the above conclusion that diffusion-controlled growth is not rate determining. Adopting an interface-controlled growth mode in the fitting, the value obtained for the activation energy for dislocation glide hindered by obstacle resistance is 112.0 ± 2.8 kJ mol À1 (see Table III), which is well compatible with the reported values for the activation energy for glide of dislocations in Cu-Ge alloys (Ge content in the range of 0.5 to 3.3. at.…”

Section: Dominant Mechanisms Of the Transformationsupporting

confidence: 85%

Kinetics of the fcc → hcp Phase Transformation in Cu-Ge Solid Solutions Upon Isothermal Aging

Polatidis

Zotov

Bischoff

et al. 2017

Metall Mater Trans A

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The kinetics of the f-phase formation from a supersaturated a-Cu(Ge) solid solution (i.e., transformation from the fcc crystal structure to the hcp crystal structure) containing 10.8 at. pct Ge [at isothermal temperatures of 573 K, 613 K, and 653 K (300°C, 340°C, and 380°C)] were studied by X-ray diffraction (XRD) for phase fraction determination. Both in situ and ex situ annealing experiments were performed. The transformation kinetics were modeled on the basis of a versatile modular model. The transformation kinetics complied with a site-saturation nucleation mode and strongly anisotropic interface-controlled growth mode in association with a corresponding impingement mode: diffusion of Ge (towards the stacking faults, SFs) does not control the transformation rate. Transmission electron microscopy (TEM) investigations showed that segregation of Ge at the stacking faults (SFs) takes place (relatively fast) prior to the structural transformation (fcc fi hcp).

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Section: Dominant Mechanisms Of the Transformationsupporting

confidence: 85%

Kinetics of the fcc → hcp Phase Transformation in Cu-Ge Solid Solutions Upon Isothermal Aging

Polatidis

Zotov

Bischoff

et al. 2017

Metall Mater Trans A

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“…Taking advantage of the relationship [49]. For the temperature range of interest (below 300°C), D Ag is only weakly dependent on temperature.…”

Section: Discussionmentioning

confidence: 99%

Precipitate stability in Cu–Ag–W system under high-temperature irradiation

et al. 2015

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a b s t r a c tThe kinetics of precipitation was investigated in the ternary Cu alloy, Cu 83.5 Ag 15 W 1.5 during irradiation with MeV Kr ions at elevated temperatures. The alloy was prepared as a solid solution by physical vapor deposition and then irradiated at room temperature to create a high density of nano-sized W precipitates. These precipitates served as effective sinks for point defects during subsequent elevated-temperature irradiation, suppressing radiation-enhanced diffusion. As a consequence the size of the Ag precipitates formed during elevated-temperature irradiation was stabilized below 20 nm, up to temperatures in excess of 300°C, thus significantly extending the regime for ''compositional patterning'' above 175°C, found for Cu 85 Ag 15 . For higher temperature irradiations (above 400°C), the role of the W precipitates in stabilizing the size of the Ag precipitates switched from simply acting as point-defect sinks to serving as pinning sites for the Ag precipitates. At 500°C, the average Ag precipitate diameter is $30 nm compared to $300 nm in the Cu 85 Ag 15 binary alloy. Rate theory calculations and kinetic Monte Carlo simulations are employed to illustrate how this transition takes place.

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